Minute particles (particulate matter) are contained in exhaust gas from a diesel engine or the like. The adverse effects on the environment when the minute particles are discharged into the atmosphere are a cause for serious concern. As a consequence, in recent years, a filter which is used to remove the minute particles from the exhaust gas (DPF) has been mounted on vehicles powered by the diesel engine or the like.
This filter is formed of ceramics or the like that are porous material which is provided with a plurality of holes which are smaller than the minute particles. This filter obstructs the passage of the minute particles, and collects the minute particles.
However, when the filter like this has been used for a prolonged period, the collected minute particles are accumulated therein and the filter becomes clogged.
In order to prevent the filter like this from becoming clogged, for example, as is shown in Patent Document 1, the method is used in which high-temperature gas is supplied to the filter so that the collected minute particles in the filter are burned and removed.
Specifically, in Patent Document 1, a burner apparatus is placed between the diesel engine and the filter. Air-fuel mixture in which exhaust gas and fuel were mixed is combusted in the burner apparatus so as to generate high-temperature gas. The minute particles are burned by supplying this high-temperature gas to the filter.